Such a front jaw is disclosed in Austrian Patent No. 351 425. The rotatable sole down-holding part is, in this known front jaw, adjustable in its vertical position for respective ski boot sole thicknesses by means of a threaded bolt. The housing of this front jaw includes a spring housing receiving a release spring and a support member attached to the spring housing. The sole down-holding part in this front jaw is yieldably maintained in its center position by an elastic block of rubber or plastic provided between the support member and the sole down-holding part, by means of which the sole down-holding part is returned to its center position after a lateral deflection.
The block of rubber or plastic in this embodiment has, in order to provide sufficient elasticity, a relatively large size or volume, thus making the jaw unnecessarily large. Furthermore, this design of a return spring cannot be used in certain state-of-the-art front jaws, because the automatic adjustment of the sole down-holding device causes the rubber block to experience a deformation even in the skiing position, and therefore it cannot dependably produce on initially calculated return force.
A further front jaw with a sole down-holding part biased by a compression spring is a state-of-the-art device shown in Austrian Patent Application No. A 1880/87, FIG. 5. This Austrian application corresponds to U.S. Pat. No. 4,960,289 issued Oct. 2, 1990 form U.S. Ser. No. 07/220 032 filed July 14, 1988. The sole down-holding part in this front jaw is moved by guide surfaces along the smooth bolt carrying the sole down-holding part, and also cannot be pivoted.
A purpose of the invention is to overcome these disadvantages of existing devices and to provide a front jaw in which the sole down-holding part can be rotated relative to the jaw housing and returns reliably to its center position after a twisting fall, even when the sole down-holding part, which is biased by a spring, is adjustable for different thicknesses of ski boot soles.